This application claims the priority of German patent document 198 47 211.4, filed Oct. 13, 1998, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a method and apparatus for operating a system for generating hydrogen-rich gas by reformation of a hydrogen containing fuel.
Unpublished German patent application by the applicant (File Number DE 197 27 589.3) describes a system for generating hydrogen-rich gas which includes a reformer for catalytic water vapor reforming of a water vapor/fuel mixture while feeding thermal energy, and a CO oxidation stage for selective catalytic oxidation of carbon monoxide from the hydrogen-rich gas while supplying heat, the reformer and the CO oxidation stage being thermally coupled. The oxygen, which is required for the selective catalytic oxidation in the CO oxidation stage, is either fed directly into the gas feed pipe or is fed directly into the CO oxidation stage. The quantity of fed oxygen is adjusted such that an atomic ratio of CO to O occurs which is between approximately 1:1 and 1:4.
It is an object of the present invention to provide a method for operating a system for generating hydrogen-rich gas in which utilization of the reforming catalyst can be improved over the whole load range and also for the entire useful life.
This and other objects and advantages are achieved by the method and apparatus according to the invention, in which the fed oxygen quantity is controlled based on the temperature in or at the output of the reformer/CO oxidation stage. In this manner, it can be ensured that the reforming catalyst is operated with a good utilization over the whole load range; that is, as the result of the fed oxygen quantity, the reaction rate in the CO oxidation stage and thus the amount of heat fed to the overall system is adjusted. By way of this control circuit, the temperature in the reformer/CO oxidation stage is kept at a defined value so that the reaction can take place independently of load changes or aging phenomena under optimal conditions.
By adjusting the oxygen quantity by means of a controlled basic quantity and an additional differential pressure control by means of the gas mixture quantity, control expenditures can be reduced.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.